An investigation of frequency domain dispersion correction of pressure bar signals

The frequency-domain method has been used for several years for the correction of dispersed experimental pressure bar signals. However, the accuracy of this method has been assessed only against assumed force–time histories of the loading function, not against a priori known loads. Further, this method presently fails to take into account predictions from the Pochammer–Chree theory for both the variation of axial strain over the bar radius, and the relation between axial stress and strain. In the current work, a known force–time history is applied to the impact face of a finite element model of a pressure bar. The dispersed signal is recorded on the bar perimeter some way from the impact face, and the frequency domain correction method applied in an attempt to re-construct the undispersed forcing function. It is demonstrated that, even for signals containing moderately high frequencies, excellent reconstruction of the forcing function can be achieved if the Pochammer–Chree results for strain variation and stress–strain relation are incorporated in the dispersion correction method.